Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 273 · 40 questions

What you do (Heat shows the secret): 1. Dip a cotton bud in lemon juice and write a secret message on white paper. 2. Let the paper dry completely — the writing disappears. 3. An adult irons the paper on a low setting while you watch from a safe distance. 4. Read the brown message and wash your hands.

1. 1.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the ironing time is the one thing we change. (a) False (b) True
2. 2.🔮 Predict: the adult irons for only one second. What happens? (a) the paper floats (b) writing turns green (c) it gets darker (d) writing stays faint
3. 3.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) almost nothing (b) blue words (c) dark brown words (d) a rainbow
4. 4.🛟 Who should use the hot iron in the secret message experiment? (a) only an adult (b) any child (c) the youngest child (d) whoever is fastest
5. 5.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) the same paper (b) the kind of juice (c) the ironing time (d) how dark the writing is
6. 6.True or false: a balloon is needed for the secret lemon message. (a) True (b) False
7. 7.🧺 Do we need a battery cell for the secret lemon message? (a) not needed (b) needed
8. 8.🍋 Secret message: who does this step — plugging in the iron? (a) a child can do it (b) an adult does it
9. 9.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) rub your eyes (b) wash your hands (c) skip washing (d) lick your fingers
10. 10.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a balloon (b) an adult with an iron (c) a small bowl (d) lemon juice
11. 11.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “how dark the writing is”? (a) we measure it (b) we change it (c) we keep it the same
12. 12.🍋 What colour does the lemon writing turn when an adult warms it? (a) blue (b) white (c) green (d) brown
13. 13.🔍 Which is the odd one out? (a) dipping the cotton bud (b) writing the message (c) putting the iron away (d) letting the paper dry
14. 14.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) the kind of juice (b) how dark the writing is (c) the ironing time (d) the iron setting
15. 15.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a magnet (b) lemon juice (c) an adult with an iron (d) white paper
16. 16.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same cotton bud”? (a) we measure it (b) we change it (c) we keep it the same
17. 17.🧺 Do we need lemon juice for the secret lemon message? (a) not needed (b) needed
18. 18.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the kind of juice is the one thing we change. (a) False (b) True
19. 19.True or false: yeast is not needed for the secret lemon message. (a) False (b) True
20. 20.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) the kind of juice (b) how dark the writing is (c) the same cotton bud
21. 21.🔍 Which is the odd one out? (a) letting the paper dry (b) plugging in the iron (c) ironing the paper (d) cutting the lemon
22. 22.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) an adult with an iron (b) a small bowl (c) a cotton bud (d) yeast
23. 23.🍋 Which of these steps is a job a child can do? (a) reading the message (b) ironing the paper (c) putting the iron away (d) cutting the lemon
24. 24.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same cotton bud is what we measure. (a) True (b) False
25. 25.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: how dark the writing is is the one thing we change. (a) False (b) True
26. 26.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a mirror (b) white paper (c) a cotton bud (d) lemon juice
27. 27.🧺 Which of these is needed for the secret lemon message? (a) a magnet (b) turmeric powder (c) an adult with an iron (d) a mirror
28. 28.🍋 Secret message: who does this step — dipping the cotton bud? (a) an adult does it (b) a child can do it
29. 29.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) the iron setting (b) how dark the writing is (c) the kind of juice
30. 30.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the ironing time is what we measure. (a) False (b) True
31. 31.🧺 Which of these is not needed for the secret lemon message? (a) a magnet (b) white paper (c) a cotton bud (d) a small bowl
32. 32.True or false: dipping the cotton bud is a job a child can do. (a) False (b) True
33. 33.True or false: an adult with an iron is not needed for the secret lemon message. (a) False (b) True
34. 34.🧺 Which of these is not needed for the secret lemon message? (a) an adult with an iron (b) a balloon (c) white paper (d) lemon juice
35. 35.True or false: a cotton bud is not needed for the secret lemon message. (a) True (b) False
36. 36.True or false: a cotton bud is needed for the secret lemon message. (a) False (b) True
37. 37.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) white paper (c) a battery cell (d) lemon juice
38. 38.🔮 Can the brown writing go back to being invisible? (a) yes, if shaken (b) no, it stays brown (c) yes, if cooled (d) yes, in the dark
39. 39.🧺 Which of these is not needed for the secret lemon message? (a) a small bowl (b) a mirror (c) a cotton bud (d) an adult with an iron
40. 40.🍋 Which of these steps is a job for an adult? (a) writing the message (b) reading the message (c) plugging in the iron (d) letting the paper dry

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